There has been a chapel at Dublin Castle since at least 1242.
The present chapel was designed by Francis Johnston and was opened, as the Anglican chapel of the Viceroy, on Christmas Day 1814. Although several times smaller than Johnston’s nearby General Post Office, it was as expensive to build. It became known as the Chapel Royal after King George IV attended service on 2 September 1821.
Following Irish independence in 1922, it lay dormant before becoming a Roman Catholic church in 1943. It is now deconsecrated. The galleries and stained glass windows are ornamented with coats of arms representing many of Ireland’s Viceroys. The arms of the last Viceroy, Lord FitzAlan Howard, filled the very last available space in the last available window when they were installed in 1922.